Definitely Nicole Mitchell. I've not heard a disappointing album by her, no matter the line up, and I've heard quite a few by now.
She visited London a couple of years ago and played Cafe Oto in duet with Mark Sanders to an embarrassingly small audience (maybe partly due to Joelle Leandre pulling out and also the Arkestra were in town). The concert was of a very high calibre, great improvising from them both. Available as a recommended download from Oto's site. I'd love to see one of her larger ensembles live